This invention relates generally to an electrophoresis system and a method for performing microfluidic manipulation. More particularly, this invention relates to a microfluidic chip and a method for electrophoretic separation.
Electrophoresis techniques are widely used in chemical and biology fields, such as DNA sequencing, protein analysis and genetic mapping. The term electrophoresis refers to a process in which charged molecules are separated in a given separation medium, such as an electrolyte solution under influence of an electric filed. The charged molecules migrate through the separation medium and separate into distinct bands due to different electrophoretic mobilities.
A variety of commercial electrophoresis apparatus have been available for analysis of a sample. One such type of the electrophoresis apparatus is a capillary electrophoresis apparatus. The capillary electrophoresis can be considered as one of the latest and most rapidly expanding techniques in analytical chemistry. It refers to a family of related analytical techniques that uses electric fields to separate molecules within narrow-bore capillaries (typically 20-100 um internal diameter).
In capillary electrophoresis, the samples may be injected into the separation capillary in advance for subsequent separation. Current practical techniques for sample injection in the capillary include electromigration and siphoning of the sample from a container into one end of the separation capillary. For the siphoning injection technique, the sample reservoir is coupled to an input end of the capillary and is raised above a buffer reservoir that is at an exit end of the capillary for a fixed length of time. The electromigration injection technique is affected by applying an appropriate polarized electrical potential across the capillary for a given duration while the input end of the capillary is in the sample reservoir. For both sample injection techniques, the input end of the analysis capillary tube must be transferred from the sample reservoir to the buffer reservoir to perform separation. Thus, a mechanical manipulation is involved. It is also difficult to maintain consistency in injecting a fixed volume of the sample by either of these techniques, as the sample volume injected are susceptible to changes in sample viscosity, temperature, etc., thereby resulting in relatively poor reproducibility in the injected sample volumes between separation runs. Electromigration additionally suffers from electrophoretic mobility-based bias.
Therefore, there is a need for a new and improved electrophoresis system and method for performing microfluidic manipulation.